1. Field of the Invention
The present invention pertains to the completion and operation of wells drilled laterally into underground formations. The invention, more especially, concerns a system of completing a horizontally disposed well in a producing formation in a manner which promotes production from the formation. The system also enables the well to be cleared of bridges and the like which may occur in the well. The invention has particular application to the production of oil and gas from subterranean formations.
2. Related Art
A continuing objective in the petroleum industry is to increase the productivity of wells drilled into petroleum-bearing formations. Another continuing objective is to minimize the need for expensive repair and workover operations caused by the occurrence of bridges and like in producing wells.
Once a well has been drilled into a petroleum bearing formation, it is a common practice to stimulate the well by hydraulic fracturing, acidizing, perforating, solvent treatments, and similar techniques. The general purpose of such techniques is to increase the effective permeability of the producing formation penetrated by the well. A related purpose is to increase the effective volume of the formation which is drained by the well. These purposes become especially important in instances where wells are very expensive to drill. This is particularly true, for example, in offshore locations where many wells may be drilled from a single offshore island or platform. It is a common practice in drilling such offshore wells to have them fan out laterally in many directions from the island or platform. These wells, therefore, will frequently extend in a generally horizontal direction into a formation.
The drilling of horizontally disposed wells is not limited to offshore locations. Wells of this nature are also drilled onshore. The more general practice onshore, however, is to drill vertical wells which extend down through the producing zone. Any sand, silt or other solids with a high density which may enter the well will then drop to the bottom "rat hole" portion of the well and cause no difficulties in producing the well. In this sense, vertical wells have had an advantage over horizontal or lateral wells in that the latter wells have been very subject to bridging The bridging material commonly consists of silt, formation particles, frac proppant, and the like.
Horizontal wells do not have a rat hole into which silt, sand and other particles may drop and accumulate. These materials, instead, accumulate along the lower side of such wells where they tend to raft up into barriers due to fluid flow. All too frequently, these barriers can completely close off the flow passage, in which case no production can be realized from behind the barriers.